Advanced Topics
In a nutshell: Cellular respiration is how cells convert food to usable energy.
## How Cells Harvest and Use Energy
Energy is essential for life, and cells extract it through metabolism. The main process for generating cellular energy is cellular respiration.
### Stages of Cellular Respiration
1. **Glycolysis:** Glucose is broken down in the cytoplasm, producing ATP and pyruvate.
2. **Krebs Cycle (Citric Acid Cycle):** Pyruvate enters mitochondria, releasing electrons and more ATP.
3. **Electron Transport Chain:** Electrons generate a proton gradient, driving ATP synthesis.
The overall equation is:
\[
C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}
\]
### Metabolic Pathways
Catabolism breaks down molecules for energy, while anabolism builds new molecules.
### Clinical Impact
Understanding metabolism helps explain diseases like diabetes, where energy extraction from glucose is impaired.
C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}
Examples
- Muscle cells increase respiration during exercise to meet energy demands.
- Mitochondrial disorders affect energy production, leading to fatigue.
Key terms
- ATP
- Adenosine triphosphate, the energy currency of the cell.
- Glycolysis
- The first stage of cellular respiration, breaking down glucose.